Protesters in Lincoln Park, 1968

Protesters as well as police braced for trouble during the 1968 Democratic National Convention in Chicago. Here, anti-Vietnam War demonstrators gather in Lincoln Park for self-defense lessons.

Protesters as well as police braced for trouble during the 1968 Democratic National Convention in Chicago. Here, anti-Vietnam War demonstrators gather in Lincoln Park for self-defense lessons. (Tribune photo by Bill Kelly)

Protesters as well as police braced for trouble during the 1968 Democratic National Convention in Chicago. Here, anti-Vietnam War demonstrators gather in Lincoln Park for self-defense lessons.